Tubing and piping are frequently used to make various structures, e.g. scaffolding, furniture, framing, etc. Such structures inevitably require the use of a tee joint wherein one piece of tubing abuts directly into a second piece of tubing at right angles to each other and the problem is to connect the two pieces into a rigid load carrying joint. There are common pipe or tubing tees which join the ends of three pieces of piping or tubing to form a tee joint. The present invention, however, is concerned with employing a single continuous tubing or piping and joining to it an abutting piece to make a tee joint.
Various constructions of tee joints have been produced in the prior art, among which are those illustrated by U.S. Pat. No. 949,108--Abel. Such a structure is produced by inserting into the end of the abutting tubing a special nut with a serrated circumference and to attach the continuous piece of tubing by means of a bolt through that tubing and engaged with such special nut. Similarily in U.S. Pat. No. 2,557,766--Ronfeldt there is such a special nut which has been formed into the end of the main tubing to hold it in place and at the same time form a partial saddle to engage the running tubing member. These devices require special nuts and the reforming of the tubing end to accommodate nuts and the piece of running tubing that is to be connected therewith.
Another construction which has been found in the prior art is illustrated by British Pat. Nos. 1,232,489--Smith and 1,497,532--Davies is to insert into the interior of the abutting tubing an expandable plug which serves as a nut, or which has a separate nut, for a connecting bolt, and as the bolt is screwed into this plug, it causes the plug to expand and to hold the plug against the inside surface of the tubing by friction.
Neither of the above two general types of construction is entirely satisfactory. The special nuts which are crimped into the end of the abutting tubing will eventually work loose and the joint will accordingly fail completely. Similarly, the expanding plugs have a tendency to become loose with time and thus to weaken the frictional forces holding the plug in place, thereby causing that type of joint to fail.
Other prior art having pertinency to this invention which were found in the search thereon are U.S. Pat. Nos. 468,963--Campbell; 501,935--Harsha; 2,972,495--Yalen; 3,519,292--Krikorian; 4,008,971--Wah et al; 4,013,372--Lay et al; and 4,083,641--Sado. None of these patents disclose or teach the invention embodied herein either alone or in any appropriate combination with any of the prior art known nor does the art alleviate the shortcomings of the prior art in the improved and effective manner set forth herein.
Accordingly, it is a general object of the present invention to provide a new and improved structural tee joint for tubing or piping. A specific object of this invention is to provide such a tee joint having a greater stability and durability than other known joints of this type. Another specific object of this invention is to provide a structural tee joint for use with plastic tubing which greatly rigidifies structures created therefrom. Other objects and advantages will appear from the more detailed description of this invention which is set forth hereinafter.